It is currently estimated that up to 9% of HIV-infected individuals are co-infected with HCV. Until the development of the HIV-1 protease inhibitors and the use of highly active anti-retroviral therapy (HAART), HIV was the survival-limiting factor in co-infected individuals. Therefore, HCV was generally not treated. With the decline in HIV-attributed morbidity and mortality secondary to HAART, treatment of HCV in co-infected individuals has become an important issue. However, the optimal dose of interferon required for HCV treatment has not been determined in HCV/HIV-1 co-infected patients. Therefore we propose the following specific aims: Aim: To compare the effect of two different interferon doses on HCV RNA levels in individuals co-infected with hepatitis C and the human immunodeficiency virus. Primary outcome: The primary outcome of this study is the decrease in the hepatitis C RNA level in response to two different doses of interferon. Study design: This study will consist of two phases. Phase I will be an interventional study and Phase II will be an observational study. During phase I, subjects will be randomized to one of two different doses of interferon-alpha which will be administered subcutaneously by self-injection. Group A subjects will recieve 9 million units daily for two weeks followed by three million units daily. Group B will receive three million units three times per week. At the end of three months of treatment, subjects will be evaluated for a response to interferon. Phase II will be an observational study to observe the variation over time in co-infected patients following different therapies. Individuals will be followed for up to a total of 52 weeks while being treated according to standard medical care as advised by the patients' physician.